#8: Cleanup & Javadoc

Signed-off-by: Dominik Säume <Dominik.Saeume@hmmh.de>

src/main/java/de/hitec/nhplus/Main.java

@@ -37,10 +37,17 @@ public class Main extends Application {
     @Override
     public void start(Stage primaryStage) {
         this.primaryStage = primaryStage;
-        executePassword();
+        User user = executeLogin();
+        if(user != null){
+            executeMainApplication(user);
+        }
     }
 
-    private void executePassword() {
+    /**
+     * Executes the login.
+     * @return User The {@link User} object for the logged-in {@link User}. Is {@code null}, if the login was not successful,
+     */
+    private User executeLogin() {
         try {
 
             FXMLLoader loader = new FXMLLoader(Main.class.getResource("/de/hitec/nhplus/login/LoginView.fxml"));
@@ -55,12 +62,10 @@ public class Main extends Application {
             controller.initialize(loginStage);
 
             loginStage.showAndWait();
-
-            if(controller.user != null){
-                executeMainApplication(controller.user);
-            }
+            return controller.user;
         } catch (IOException exception) {
             exception.printStackTrace();
+            return null;
         }
     }